7.7 Earthquake Strikes Panama, Damage Expected

Scientific American reports that a magnitude 7.7 earthquake struck Panama on Friday afternoon. The U.S. Geological Survey initially measured the quake at 8.0 but later downgraded it to 7.7. The epicenter was about 9 miles southwest of Pitaloza Arriba, a small village in Herrera Province.

Around 4.6 million people experienced moderate to severe shaking, the USGS estimates. No statistics on injuries or deaths have been released yet. The affected area has relatively low population density.

Panamanian President Jose Raul Mulino said on social media that he had instructed the mobilization of personnel, resources and aid.

The earthquake occurred on land at a shallow depth. USGS seismologist Susan Hough told Scientific American that this reduced the tsunami risk. "Because this was on land and shallow, you're not on the seafloor, so it didn't move the seafloor underneath the water column and that's what you need to generate a tsunami," she said. The U.S. National Oceanic and Atmospheric Administration's Tsunami Warning System did not issue any tsunami alert.

Shallow earthquakes do cause stronger shaking at the surface. USGS modeling suggests the quake could cause dozens to hundreds of fatalities and hundreds of millions of dollars in damage.

The quake was a shallow lateral fault, or strike-slip fault, similar to the San Andreas, Hough said. Panama sits near the intersection of several tectonic plates: the Cocos and Nazca plates to the south, the Caribbean plate to the north, and the South American plate to the east. Subduction zones near Panama do not meet, which is why the country usually experiences less powerful quakes, Hough explained. This earthquake was "quite large compared to other earthquakes that have been seen in that area."

The U.S. embassy in Panama warned U.S. citizens to avoid damaged structures and the coast and to monitor local emergency broadcasts.